Vacuum tube



Nov. 16, 1937.

W. G. TAYLOR VACUUM TUBE Filed July 9, 1936 Patented Nov. 16, 1937 UNITED STATES PATENT oEEIcE VACUUM TUBE Warren G. Taylor, Chicago, Ill.

Application July 9, 1936, Serial No. 89,781

9 Claims. (Cl. 25o-27.5)

This invention relates to vacuum tubes and particularly to vacuum tubes for use at extremely high frequencies and high potentials. Tubes under such conditions are used in short wave radio and also in diathermy and for surgical operations with the so called electric knife. In the latter instance the tubes are subjected to unusually hard usage, ranging from a zero load up to a short circuit. The potentials and frequency used 10 on the tubes are such that the customary tube has had in many instances a short life.

It is an object of this invention to devise a tube construction in which extremely high frequencies will not result in high losses in the glass of the tube and in which high potentials under such conditions will not result in damage to the tube. An

additional object is to devise aheavy duty tube construction wherein the supporting frame work for ther electrodes is electrically k neutral and wherein no great differences of potential are impressed directly through the walls of the glass. Other objects will become apparent as the description proceeds.

Referring to the drawing:

' Figure l showsan elevation of a tube embodying this construction with certain portions broken away.'

Figure 2 is a section on line 2-2 of Figure 1.

Figure 3 is a section on line 3-3 of Figure 2.

The tube comprises` a glass bulb I having a reentrant stem 2 coming up from the bottom and a smaller reentrant stem 3 coming down from the top of the tube. The entire electrode construction is supported around stem 2 by means of a wide metal band 5 clamped by a bolt 6 in the usual fashion. Carried by band 5 are four spaced upright metal rods 1 to Ill inclusive which run Well up toward the top of the tube. Threaded through these four rods and disposed-above stem 2 is an insulator I2 here shown as circular but which may be rof any desired shape. The free ends of rods 1 to II) inclusive are threaded through another insulator I3 similar `to I2. The entire electrode structure 'is assembled between these two insulators I2 and I3 and together with theseinsulators forms a rigid construction removable as a unit from the tube. y

Between insulators I2 and|3 an anode I5 is provided of any shape whatsoever. As shown here the anodel is preferably of carbon having an elongated'interior chamber I6 and a pair of wings yI1 and I 8 extending from the opposite sides thereof. Wings I1 and I8 are'apertured and through these pass supporting rods and 2|, these rods 55 passing through suitable apertures in insulators I2 and I3. It will be noted that due to the location of wings I1 and I8 from the center of each anode wall that both rods 20 and 2| are spaced from the four rods 1 td Il) inclusive. Disposed around rods 20 and 2| are sleeves 22 to 25 inclu- 5 sive. These sleeves extend from the inside insulator surface to the anode ends and serve to maintain the anode in a xed vertical position as seen in Figure 1. Rods 20 and 2| have their bottom ends 26 and 21 distorted for locking purposes. l0

Rods 20 and 2| are bent inwardly at the top at 28 and 29 and terminate in a strap 3D disposed around small press 3. A lead 3| is sealed in small stem 3 and is welded to rod 2|. Lead 3| has a metal cap 32 on the outside of the tube connected 15 thereto to which the anode supply may be connected.

Disposed within anode I5 is a grid 35 of the usual wire construction wound around grid posts 36 and 31. These grid posts may projectv into 20 apertures 38 and 39 in tube insulator I3 and at the bottom pass through similar apertures 40 and 4| in the bottom insulator I2. The bottom ends of grid post 36 and 31 extending below insulator I2 are preferably joined by a Wire 42 from which extends a lead 43. This lead is sealed in the bottom of press 2 at 44 and passes therethrough.

Within grid 35 a lamentary cathode 48 is provided. This cathode is bent into the shape of Van M and has its ends joined to a pair of heavy wires 30 49 and 50 tightly pressed through apertures 52 and 53 in bottom insulator I2. The free ends 49 and 5I]l of the filament are joined to leads 55 and 56 sealed in press 2.

The bottom bight 51 of the fllament is retained 35 by a hook 58 carried by a looped spring 59 anchored in the center of insulator I2. The top bights 60 and 6I of the filament are maintained taut by hooks 62 and 63 passing through top insulator I3 and tensioned by coil springs 64 and 65. 40 It is clear that the electrode assembly comprising the insulators I2 and I3 with posts 29 and 2| together with the grid and filament may be assembled and inserted into the tube as a unit. The four posts 1 to I0 inclusive are threaded through .45 the two insulators and thereafter crossbars 61 and 68 are welded to rods 1 and I9 and 8 and 9 respectively. This makes the skeleton frame work more rigid and anchors the assembly.

After the electrode assembly has been positioned in the tube, upper strap 30 is adjusted over upper press 3. The rods 20 and 2| may be moved downwardly so that strap 30 may be disposed just below the tip of press 3, it being understood, of course, that lead 3| is straight at this time, and 55,

then the strap may be pulled upwardly until the bumps 26 and 21 on the bottoms of these rods limit them. The cathode grid connections may then be made at the bottom and the anode connection may be made at the top as shown.

It is evident that strap 5 and the four rods l to ill inclusive are not directly connected to any electrode and hence are at no definite potential with respect to the electrodes. The strap which has been customarily at the anode potential butl which in this instance is at no denite poten-tial has no tendency to set up electrostatic strains through the glass wall of press 2.

strain due to the grid cathode potential is distributed over a large glass surface. It is understood, of course, that the wires coming from thel seal and exposed to the atmosphere may be insu-vl latedY in any suitablermanner, such as glass tubes or the like.

` Byrproviding the anode lead at the top of the tube the greatest difference in potentialA is impressed across the entire bulb.

A construction of this character has been found to be very sturdy mechanically and electrically and has successfully been operated under conditions where the usual construction `frequently broke down. It must be remembered that the insulating qualities of glass diminish very rapidly with increase in temperature. 'In the ordinary construction considerable di-electric losses at extremely high frequencies in glass tend to generate heat therein at the press where the strap is located. When a tube of this type is overloaded, the increase in heat at the press reduced the insulating qualities of the glassycausi ing more losses and resulting in a direct lpuncture. With this construction even an extreme overload has no appreciable effect.V

What is claimed is: Y

1. A vacuum tube comprising an evacuated bulb having a reentrant stem at the two ends thereof, a metal strap disposed aroundeach'stem, a plurality of rods extending from each stem toward the other stem, said rods being mecha'n'i-r cally and electrically distinct from each other with the rods from the lower strapbeing electrically neutral to all tube electrodes, a pair of insulating discs threaded through the rods from the lower strap, an anode supported by said rods from said upper stern, said anode being supported between said insulators, a grid and filamentary cathode supported by said insulating discs within said anode, and connections sealed in said bottom stem for said cathode and grid.

2. The structure of claim 1 wherein said grid vconnection passes through the bottom of said bottom stern and wherein said filament connections pass through the free end of said bottom stem.

3. In an electron discharge device, an evacuated bulb having a reentrant stem terminating in a press at one end thereof, afmetal strap disposed around said stem, a plurality of metal supporting rods carried by said strap and forming a framework extending toward the otherend of said bulb, an electrode assembly insulatingly supported by said framework, said assembly comprising a pair of spaced insulators threaded over the wires of said framework and being the only elements of the entire electrode assembly touched by said framework, an anode supported between said insulators, a grid disposed within said anode and supported between said insulators, acathode By providingi.` the grid lead as shown through the side of.l the,` bottom of press 2 it is clear that the electrostaticl disposed within said grid and supported between said insulators, cathode leads sealed in said press and connected to the cathode terminals, a lead sealed in the stem remote from said press, another lead sealed in said bulb remote from both stem and press, and electrically separate'connections between said grid and anode to said two leads.

4. In an electron discharge device, an evacu ated bulb having a reentrant stem terminating in a press at one end thereof, a. metal strap disposed around said stem, a plurality of metal supporting rods carried by said strap and formingV a framework extending toward the other end of said bulb, an electrode assembly insulatingly carried by said framework, said electrode V assembly comprising a pair of spaced flat insulators threaded over said framework and formvingthe sole mechanical element of the entire electrode assembly touched by said framework, an anode, means for supporting said anode between said spaoed insulators, a grid within said anode, means for'supporting said grid between said spaced insulators, a cathode within said grid, means for supporting said cathode between said spaced insulators, leads sealed in said press connected to said cathode, a lead sealed in said stemV remote from said press connected to said grid, andv a lead sealed in said bulb remote from both press and stem and connected to said anode. 5. In an electron discharge device, an evacuated bulb having a reentrant stem terminating in a press at one end thereof, a metal strap disposed around said stem, a plurality of metal supporting rods carried by said strap and forming a framework extending toward the other end of said bulb, an electrode assembly insulatingly supported by said framework and comprising a pair of flat i-nsulators threaded over said framework and forming the sole mechanical connecting medium between said electrode assembly and framework, an anode disposed between said insulators, wires passing through said insulators and anode for maintaining said anode between said insulators, a grid disposed within said anode, leads sealed in'said press and connected to the cathode, a lead sealed in said stem remote from said press and connected to said grid, and a lead sealed in said bulb remote from both stem and press and connected to at least one of the anode supporting wires.

6. In an electron discharge device, an evacuated bulb having a reentrant stem terminating in' a press at each of the opposite ends thereof, a metal strap disposed around one stern, a plu'- rality of metal supporting members carried by said strap and forming a framework extending toward the other stem, an electrode assembly insulatingly supported by said framework and com-v prising a pair of spaced insulators engaged by said framework and being the only element of said electrode assembly contacted by said frameaway from said second stem, and connections for said cathode grid and anode electrodes.

'7. The tube of claim 6 wherein leads sealed in said rst press are connected to said cathode, a lead sealed in said rst stem remote from said rst press is connected to said grid, and wherein a lead sealed in said second press is connected to one of the anode supporting rods.

8. In an electron discharge device, an evacuated bulb having a reentrant stem terminating in a press at one end thereof, a metal strap disposed around said stem, a plurality of metal supporting rods carried by said strap and forming a framework extending toward the other end of said bulb, an electrode assembly insulatingly supported by said framework and comprising a, pair of spaced insulators threaded over said framework and forming the only elements of said electrode assembly touched by said framework, an anode between said insulators, Wire rods threaded through said insulators and anode for maintaining said anode between said insulators, a grid disposed within said anode and supported between said insulators, a cathode disposed Within said grid and supported between said insulators, leads sealed in said press and connected to said cathode, a lead sealed in said stem remote from said press and connected to said grid, a lead sealed in said bulb remote from said stem and press and connected to one of said anode supporting rods, and means for supporting the electrode assembly end remote from said press and from the bulb end opposite said stem.

9. In an electron discharge device, an evacuated bulb having a reentrant stem terminating in a press at one end thereof, a metal strap disposed around said stem, a plurality of metal supporting members carried by said strap and forming a framework extending toward the other end of said bulb, an electrode assembly insulatngly supported by said framework, said assembly comprising a pair of spaced insulators engaged by said framework membersand being the only elements of the entire electrode assembly touched by said framework, an anode supported between said insulators, a grid within said anode and supported between said insulators, a cathode disposed within said grid and supported between said insulators, cathode leads sealed in said press and connected to the cathode terminals, a lead sealed in the stem remote from said press and connected to said grid, and another l'ead sealed in said bulb remote from both stem and press and connected to said anode.

WARREN G. TAYLOR. 

